linux-kernel - Re: [PATCH v12 27/28] drm/rockchip: inno

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Date: Tue, 7 May 2024 09:32:16 +0800
From: Andy Yan <andy.yan@...k-chips.com>
To: Maxime Ripard <mripard@...nel.org>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
 Daniel Vetter <daniel@...ll.ch>, Jonathan Corbet <corbet@....net>,
 Sandy Huang <hjc@...k-chips.com>, Heiko Stübner
 <heiko@...ech.de>, Chen-Yu Tsai <wens@...e.org>,
 Jernej Skrabec <jernej.skrabec@...il.com>,
 Samuel Holland <samuel@...lland.org>, Hans Verkuil <hverkuil@...all.nl>,
 Sebastian Wick <sebastian.wick@...hat.com>,
 Ville Syrjälä <ville.syrjala@...ux.intel.com>,
 dri-devel@...ts.freedesktop.org, linux-arm-kernel@...ts.infradead.org,
 linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-media@...r.kernel.org, linux-rockchip@...ts.infradead.org,
 linux-sunxi@...ts.linux.dev
Subject: Re: [PATCH v12 27/28] drm/rockchip: inno_hdmi: Switch to HDMI
 connector

Hi Maxime,

On 5/6/24 15:59, Maxime Ripard wrote:
> Hi Andy,
> 
> Thanks a lot for giving it a try
> 
> All the issues you raised in your review are fixed.
> 
> On Sat, Apr 27, 2024 at 06:44:54PM GMT, Andy Yan wrote:
>> And after this whole series applied on linux 6.9-rc4, the display on rk3036 kylin is lost, I get
>> the following error:
>> [  178.999421] rockchip-drm display-subsystem: [drm:drm_atomic_check_only] checking 87b7fbde
>> [  178.999471] rockchip-drm display-subsystem: [drm:drm_atomic_helper_check_modeset] [CRTC:35:crtc-0] mode changed
>> [  178.999498] rockchip-drm display-subsystem: [drm:drm_atomic_helper_check_modeset] [CRTC:35:crtc-0] enable changed
>> [  178.999521] rockchip-drm display-subsystem: [drm:drm_atomic_helper_check_modeset] [CRTC:35:crtc-0] active changed
>> [  178.999547] rockchip-drm display-subsystem: [drm:drm_atomic_helper_check_modeset] Updating routing for [CONNECTOR:37:HDMI-A-1]
>> [  178.999575] rockchip-drm display-subsystem: [drm:drm_atomic_helper_check_modeset] [CONNECTOR:37:HDMI-A-1] using [ENCODER:36:TMDS-36] on [CRTC:35:crtc-0]
>> [  178.999604] rockchip-drm display-subsystem: [drm:drm_atomic_helper_connector_hdmi_check] Trying with a 8 bpc output
>> [  178.999636] rockchip-drm display-subsystem: [drm:drm_atomic_helper_connector_hdmi_check] Trying RGB output format
>> [  178.999730] rockchip-drm display-subsystem: [drm:drm_atomic_helper_connector_hdmi_check] RGB Format, checking the constraints.
>> [  178.999757] rockchip-drm display-subsystem: [drm:drm_atomic_helper_connector_hdmi_check] RGB output format not supported with 8 bpc
>> [  178.999783] rockchip-drm display-subsystem: [drm:drm_atomic_helper_connector_hdmi_check] Failed. No Format Supported for that bpc count.
>> [  178.999810] rockchip-drm display-subsystem: [drm:drm_atomic_helper_check_modeset] [CONNECTOR:37:HDMI-A-1] driver check failed
>> [  178.999836] rockchip-drm display-subsystem: [drm:drm_atomic_check_only] atomic driver check for 87b7fbde failed: -22
>> [  178.999868] rockchip-drm display-subsystem: [drm:drm_atomic_state_default_clear] Clearing atomic state 87b7fbde
>> [  178.999898] [drm:drm_mode_object_put] OBJ ID: 37 (4)
>> [  178.999922] [drm:drm_mode_object_put] OBJ ID: 37 (3)
>> [  178.999944] [drm:drm_mode_object_put] OBJ ID: 40 (1)
>> [  178.999971] [drm:drm_mode_object_put] OBJ ID: 39 (2)
> 
> Which kind of display are you testing with? The only reason it could do
> so is if the display claim it doesn't support RGB in its EDID which is
> contradicting the HDMI spec. Are you using an Analog display by any
> chance? or the built-in EDIDs through the drm.edid_firmware mechanism?
> 

It is because there is something wrong(I still don't know why) with the DDC on my board.
It always failed to read edid when it first bootup, that means inno_hdmi_connector_get_modes
will return 0.

and in function

drm_helper_probe_single_connector_modes:

         count = drm_helper_probe_get_modes(connector);

         if (count == 0 && (connector->status == connector_status_connected ||
                            connector->status == connector_status_unknown)) {
                 count = drm_add_modes_noedid(connector, 1024, 768);

                 /*
                  * Section 4.2.2.6 (EDID Corruption Detection) of the DP 1.4a
                  * Link CTS specifies that 640x480 (the official "failsafe"
                  * mode) needs to be the default if there's no EDID.
                  */
                 if (connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort)
                         drm_set_preferred_mode(connector, 640, 480);
         }
drm_add_modes_noedid will not initialize display_info.

> Maxime